The loss of nitrogen and phosphate fertilizers in agricultural runoff is a global environmental problem, attracting worldwide attention. In the last decades, the constructed wetland has been increasingly used for mitigating the loss of nitrogen and phosphate from agricultural runoff, while the substrate, plants, and wetland structure design remain far from clearly understood. In this paper, the optimum substrates and plant species were identified by reviewing their treatment capacity from the related studies. Specifically, the top three suitable substrates are gravel, zeolite, and slag. In terms of the plant species, emergent plants are the most widely used in the constructed wetlands. Eleocharis dulcis, Typha orientalis, and Scirpus validus are the top three optimum emergent plant species. Submerged plants (Hydrilla verticillata, Ceratophyllum demersum, and Vallisneria natans), free-floating plants (Eichhornia crassipes and Lemna minor), and floating-leaved plants (Nymphaea tetragona and Trapa bispinosa) are also promoted. Moreover, the site selection methods for constructed wetland were put forward. Because the existing research results have not reached an agreement on the controversial issue, more studies are still needed to draw a clear conclusion of effective structure design of constructed wetlands. This review has provided some recommendations for substrate, plant species, and site selections for the constructed wetlands to reduce nutrients from agricultural runoff.

To mitigate the urban heat island (UHI) and release the low carbon potential of green walls, we analyzed the cooling and energy-saving performance of different green wall designs. Envi-met was applied as the main simulation tool, and a pedestrian street named Yuhou Street was selected as the study object. Four designs of walls were summarized and simulated, demonstrating the living wall system (LWS). Super soil had superiority in cooling and energy saving. Outdoor air temperature, indoor air temperature, outside wall surface temperature, and inside wall surface temperature were analyzed. Apart from the outdoor air temperature, the other three temperatures were all significantly affected by the design of green walls. Finally, energy savings in building cavities were determined. The indoor energy saving ratio of the LWS based on super soil reached 19.92%, followed by the LWS based on boxes at 15.37%, and green facades wall at 6.29%. The indoor cooling powers on this typical day showed that the cooling power of the LWS based on super soil was 8267.32 W, followed by the LWS based on boxes at 6381.57 W, and green facades wall at 2610.08 W. The results revealed the difference in cooling and energy-saving performance of different green walls in this typical hot summer area.

Vegetation has been considered as an effective strategy to combat the urban heat island effect. Most researches have focused on evaluating the cooling effect of trees in the urban thermal environment, while little attention has been paid to the cooling effect of the vegetation combinations. Moreover, most studies are focused on the horizontal cooling performance of plants, ignoring their vertical influence. Therefore, this study evaluates the 3D (horizontal and vertical) cooling performances of the three vegetation combination scenarios in the urban area using the ENVI-met model. The study indicates that the tree-grass (TG) combination has the best 3D cooling effect, followed by the tree-shrub-grass (TSG) combination, while the shrub-grass (SG) combination has the weakest 3D cooling effect. Besides, it is economical to plant TSG combinations because fewer trees are needed than planting TG combinations. Therefore, the study recommends the tree-shrub-grass combination rather than TG or SG combination in urban areas to effectively improve the thermal environment. The study also shows that the relationship between increasing tree coverage and the resulting cooling effect is not linear. The results of this study can effectively guide the design of greening strategies in urban areas to improve thermal comfort.